diff --git a/lib/MqttClient.js b/lib/MqttClient.js
index ba0d818..3424113 100644
--- a/lib/MqttClient.js
+++ b/lib/MqttClient.js
@@ -162,7 +162,7 @@ MqttClient.prototype.cleanName = function (name) {
  */
 MqttClient.prototype.close = function (cb) {
   if (this.closed) {
-    throw Error('Client already closed')
+    cb()
   }
 
   this.closed = true
diff --git a/package-lock.json b/package-lock.json
index 5365a63..1373dfa 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1303,8 +1303,7 @@
     "base64-js": {
       "version": "1.3.0",
       "resolved": "https://registry.npmjs.org/base64-js/-/base64-js-1.3.0.tgz",
-      "integrity": "sha512-ccav/yGvoa80BQDljCxsmmQ3Xvx60/UpBIij5QN21W3wBi/hhIC9OoO+KLpu9IJTS9j4DRVJ3aDDF9cMSoa2lw==",
-      "dev": true
+      "integrity": "sha512-ccav/yGvoa80BQDljCxsmmQ3Xvx60/UpBIij5QN21W3wBi/hhIC9OoO+KLpu9IJTS9j4DRVJ3aDDF9cMSoa2lw=="
     },
     "basic-auth": {
       "version": "2.0.1",
@@ -2006,9 +2005,9 @@
       },
       "dependencies": {
         "minimist": {
-          "version": "1.2.0",
-          "resolved": "https://registry.npmjs.org/minimist/-/minimist-1.2.0.tgz",
-          "integrity": "sha1-o1AIsg9BOD7sH7kU9M1d95omQoQ="
+          "version": "1.2.5",
+          "resolved": "https://registry.npmjs.org/minimist/-/minimist-1.2.5.tgz",
+          "integrity": "sha512-FM9nNUYrRBAELZQT3xeZQ7fmMOBg6nWNmJKTcgsJeaLstP/UODVpGsr5OhXhhXg6f+qtJ8uiZ+PUxkDWcgIXLw=="
         }
       }
     },
@@ -5783,41 +5782,32 @@
       }
     },
     "mqtt": {
-      "version": "2.18.8",
-      "resolved": "https://registry.npmjs.org/mqtt/-/mqtt-2.18.8.tgz",
-      "integrity": "sha512-3h6oHlPY/yWwtC2J3geraYRtVVoRM6wdI+uchF4nvSSafXPZnaKqF8xnX+S22SU/FcgEAgockVIlOaAX3fkMpA==",
+      "version": "4.1.0",
+      "resolved": "https://registry.npmjs.org/mqtt/-/mqtt-4.1.0.tgz",
+      "integrity": "sha512-dBihVZzaB8p9G/2ktSfamiaHmMnpCpP2du08317ZuEX1kBAbZOG9aMJQ11EChXnOX3GKUeiZYaSITueceQKT2A==",
       "requires": {
+        "base64-js": "^1.3.0",
         "commist": "^1.0.0",
         "concat-stream": "^1.6.2",
+        "debug": "^4.1.1",
         "end-of-stream": "^1.4.1",
         "es6-map": "^0.1.5",
         "help-me": "^1.0.1",
         "inherits": "^2.0.3",
         "minimist": "^1.2.0",
-        "mqtt-packet": "^5.6.0",
+        "mqtt-packet": "^6.0.0",
         "pump": "^3.0.0",
         "readable-stream": "^2.3.6",
         "reinterval": "^1.1.0",
-        "split2": "^2.1.1",
+        "split2": "^3.1.0",
         "websocket-stream": "^5.1.2",
         "xtend": "^4.0.1"
       },
       "dependencies": {
         "minimist": {
-          "version": "1.2.0",
-          "resolved": "https://registry.npmjs.org/minimist/-/minimist-1.2.0.tgz",
-          "integrity": "sha1-o1AIsg9BOD7sH7kU9M1d95omQoQ="
-        },
-        "mqtt-packet": {
-          "version": "5.6.1",
-          "resolved": "https://registry.npmjs.org/mqtt-packet/-/mqtt-packet-5.6.1.tgz",
-          "integrity": "sha512-eaF9rO2uFrIYEHomJxziuKTDkbWW5psLBaIGCazQSKqYsTaB3n4SpvJ1PexKaDBiPnMLPIFWBIiTYT3IfEJfww==",
-          "requires": {
-            "bl": "^1.2.1",
-            "inherits": "^2.0.3",
-            "process-nextick-args": "^2.0.0",
-            "safe-buffer": "^5.1.0"
-          }
+          "version": "1.2.5",
+          "resolved": "https://registry.npmjs.org/minimist/-/minimist-1.2.5.tgz",
+          "integrity": "sha512-FM9nNUYrRBAELZQT3xeZQ7fmMOBg6nWNmJKTcgsJeaLstP/UODVpGsr5OhXhhXg6f+qtJ8uiZ+PUxkDWcgIXLw=="
         },
         "pump": {
           "version": "3.0.0",
@@ -12744,11 +12734,23 @@
       }
     },
     "split2": {
-      "version": "2.2.0",
-      "resolved": "https://registry.npmjs.org/split2/-/split2-2.2.0.tgz",
-      "integrity": "sha512-RAb22TG39LhI31MbreBgIuKiIKhVsawfTgEGqKHTK87aG+ul/PB8Sqoi3I7kVdRWiCfrKxK3uo4/YUkpNvhPbw==",
+      "version": "3.1.1",
+      "resolved": "https://registry.npmjs.org/split2/-/split2-3.1.1.tgz",
+      "integrity": "sha512-emNzr1s7ruq4N+1993yht631/JH+jaj0NYBosuKmLcq+JkGQ9MmTw1RB1fGaTCzUuseRIClrlSLHRNYGwWQ58Q==",
       "requires": {
-        "through2": "^2.0.2"
+        "readable-stream": "^3.0.0"
+      },
+      "dependencies": {
+        "readable-stream": {
+          "version": "3.6.0",
+          "resolved": "https://registry.npmjs.org/readable-stream/-/readable-stream-3.6.0.tgz",
+          "integrity": "sha512-BViHy7LKeTz4oNnkcLJ+lVSL6vpiFeX6/d3oSH8zCW7UxP2onchk+vTGB143xuFjHS3deTgkKoXXymXqymiIdA==",
+          "requires": {
+            "inherits": "^2.0.3",
+            "string_decoder": "^1.1.1",
+            "util-deprecate": "^1.0.1"
+          }
+        }
       }
     },
     "sprintf-js": {
@@ -14036,9 +14038,9 @@
       "dev": true
     },
     "websocket-stream": {
-      "version": "5.5.0",
-      "resolved": "https://registry.npmjs.org/websocket-stream/-/websocket-stream-5.5.0.tgz",
-      "integrity": "sha512-EXy/zXb9kNHI07TIMz1oIUIrPZxQRA8aeJ5XYg5ihV8K4kD1DuA+FY6R96HfdIHzlSzS8HiISAfrm+vVQkZBug==",
+      "version": "5.5.2",
+      "resolved": "https://registry.npmjs.org/websocket-stream/-/websocket-stream-5.5.2.tgz",
+      "integrity": "sha512-8z49MKIHbGk3C4HtuHWDtYX8mYej1wWabjthC/RupM9ngeukU4IWoM46dgth1UOS/T4/IqgEdCDJuMe2039OQQ==",
       "requires": {
         "duplexify": "^3.5.1",
         "inherits": "^2.0.1",
diff --git a/package.json b/package.json
index de70874..8b8bd51 100644
--- a/package.json
+++ b/package.json
@@ -70,7 +70,7 @@
     "install": "^0.12.2",
     "jsonfile": "^5.0.0",
     "morgan": "~1.9.0",
-    "mqtt": "^2.18.8",
+    "mqtt": "^4.1.0",
     "mqtt-nedb-store": "^0.1.1",
     "mqtt-wildcard": "^3.0.9",
     "nedb": "^1.8.0",